Method and apparatus for diagnosing a pump system

ABSTRACT

An apparatus and method for diagnosing rotating equipment commonly used in the factory and process control industry are provided. The apparatus and method are intended for use in assisting a maintenance engineer in the diagnosis of turbines, compressors, fans, blowers and pumps. The preferred embodiments are an apparatus and method for diagnosing pumps, with a focus on centrifugal pumps. The apparatus and method are based on the comparison of the current pump signature curves resulting from the acquisition of process variables from sensors monitoring the current condition of the pump and the original or previous pump performance curve from prior monitoring or knowledge of the pump geometry, installation effects and properties of the pumped process liquid. The diagnostic apparatus and method can be applied to any rotating machine, but the apparatus and method for pumps are described herein.

This is a divisional application of copending Ser. No. 09/002,053 filedDec. 31, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for diagnosing apump system.

2. Background

Pumps are among the least reliable components in a process plant withthe average Mean Time To Repair (MTTR) averaging two years. Recentadvances in vibration sensor based condition monitoring are nowroutinely used to measure the vibration profile of a pump system todetermine if large velocity or acceleration vibration levels arepresent. Such vibration levels are indicative of a failed or failingpump.

Pump maintenance is most often required due to operating a pump underconditions where bearing loads are high and where there is fluid induceddamage to the impeller, i.e., cavitation and recirculation. Thedesirability of operating at the pump's Best Efficiency Point (BEP) iswell known in the pump industry. At the BEP, bearing forces are designedto be at a minimum, vibration levels are lowest, and cavitation andrecirculation are avoided. Examples of the impact on pump life due tooff-BEP operation can be found in Pump Characteristics and Applicationsby M. S. Volk.

No commercial product, method or system has the ability to provide anoperator or maintenance engineer with the actual operating pumpperformance curve and process operating point. An understanding of theoperating point or range versus the intended operating range on a pumpperformance curve is key to operating a pump near its BEP and todiagnosing pump component damage when operating in off-BEP regions.

Vibration monitoring equipment such as that provided by Bently Nevada iswell-known for condition monitoring of rotating equipment. The BentlyNevada system consists of sensors (typically accelerometers,displacement sensors, proximity velocity transducers and temperaturesensors) that are appropriately mounted to rotary equipment such asturbines, compressors, fans, pumps and drive units such as motors.

Monitoring machine performance through vibration signature analysis is apractice spanning more than two decades. Many standards used for overallvibration measurements are based on specific rotational frequencies andinteger multiples of these specific rotational frequencies. Vibrationdata is routinely collected either manually or with on-line systems frombearings on rotating machines. Bearing vibration measurements shouldinclude measurements in both the horizontal and vertical planes of eachbearing. At least one axial vibration is made for each shaft.

Vibration readings on the bearing housing, using an accelerometer(acceleration) or a velocity transducer (velocity), provide sufficientdata to detect the onset of bearing failure. Displacement or proximityprobes measuring the motion the shaft relative to the bearing alsoprovide useful data for diagnosing bearing failure. The motion of theshaft within the bearing as measured by the proximity sensor is commonlycalled an “orbit”.

Rotating machines and pumps, by their very nature are dynamic machines.Vibration and proximity sensor data is also dynamic and is typicallycollected as trend data, FFT and waveforms. Most faults are identifiedby distinct frequency peaks or patterns and therefore frequency bandsmay be defined which bracket specific faults. These bands may bespecifically scanned for amplitude changes which signal the need forfurther analysis. These scans will include comparing recorded vibrationlevels against alarm levels as well as a statistical analysis ofvariation and comparison to baseline values. The defined frequency bandswill include the calculated or measured resonant frequencies of themajor rotating machine mechanical components such as the shaft,impeller, radial bearings and thrust bearings. Analysis of vibrationaldata to identify known faults are further described in the CSIApplication paper:

“Vibration Monitoring of Common Centrifugal Fans in Fossil Fired PowerGeneration”.

Further analysis will include a review of the amplitude and phase versusfrequency spectra, sometimes a referred to as the Bode plot, for theproximity and vibration sensors. Multiples of the machine componentresonant frequencies, commonly termed harmonics, are also examined.

These known vibration monitoring techniques are applied in combinationwith the rotating machine performance curves to provide for root causeanalysis the rotating machine in a method previously not performed.

The sensors are mounted for the purpose of detecting impending motorbearing or pump bearing failures through sensor signal analysis usingconventional spectral analysis such as the Fast Fourier Transform (FFT).

The use of a vibration spectra is well known, but such use oftenrequires a human expert to examine the spectra and deduce damage. Expertanalysis is required since the frequency components for all of themechanical components (bearings, impeller, piping, etc.) are all presentat the same time. Therefore, discrimination of the vibration bycomponent requires substantial skill. As vibration sensors provide aspectral output (frequency domain), the vibration peaks correspond to amultiplicity of failure modes that may be present at the same time. Asingle vibration spectra is likely to show the shaft frequency, impellerfrequency, radial bearing fundamental frequency, thrust bearingfundamental frequency, motor harmonic frequency, pump/piping resonantfrequency, mounting plate frequency, etc. In addition to thesefundamental frequencies, the harmonics or multiples, and submultiples ofthese frequencies will also be present.

Traditional condition monitoring systems are used to detect damage thathas already occurred to a rotating machine. The pump diagnostics methodis able to detect rotating machine operating conditions that may lead topump damage. The pump diagnostics method also provides an ability tofocus the maintenance engineer or technician to examine a specific areaof vibration spectra for evidence of a pending failure detected throughknowledge gained from the pump performance signature.

Additional analysis is provided through the measurement of the pump tomotor shaft alignment using position or proximity sensors and throughthe measurement of the shaft “orbit” within the bearing. Temperaturemeasurements are strategically positioned to provide data on bearing“hot spots”. Bently's system provides for off-line or “pseudo real time”acquisition of the above data and field processing of the sensor dynamicdata which can be communicated to a centrally located display forviewing either via a proprietary communication or the Modbus protocol.Real time analysis has not been possible in the past due to bandwidthlimitations in communications protocols.

Vibration sensors (piezoelectric accelerometers, velocity transducersand proximity sensors) are available from many suppliers such as BentlyNevada, Vibrametrics, Dytram and CSI and are often used with FFTalgorithms for determination of vibration spectra for rotary equipment.

Vibration monitoring systems are available in portable “walk around”versions versus in situ systems where the vibration spectra is measuredperiodically. These portable vibration systems can provide for diagnosisof bearing failure, but are not as effective in determining the “rootcause” for the bearing failure.

A diagnostics method is needed that provides for guidance in the repairof a failing pump, but most importantly, provides the operator with aroot cause analysis that enables elimination of the cause of failure,which is often operation of the pump outside the BEP range. Availablecondition monitoring-only solutions provide limited guidance onelimination of the cause of failure as they observe the failure of themechanical components, but do not identify the operating condition thatcaused the failure.

a. Electric Motor Diagnostics

Several manufacturers provide partial solutions for the off-linediagnosis of electric motors. Framatome and Liberty Technologies bothprovide for PC based electric motor diagnostics systems consisting ofvibration sensors to detect motor bearing failure, a measurement ofmotor voltage wherein current and phase are coupled to an FFT for thecalculation of a motor signature, and temperature sensors to senseelevated motor winding temperatures and, in some cases, flux analysis,and insulation characteristics of the motor windings and shaft alignmentsensors to measure motor-to-coupler alignment.

CSI has recently announced a motor diagnostic system that provides datalogging of key motor diagnostic attributes that are manually collectedand uploaded to a PDM device at regular intervals.

Siemens has a smart motor system that provides pseudo real-timediagnostics information such as that summarized above via a sensorsystem connected to a field mounted motor analysis computer.

Current motor diagnostics systems capture only motor and motor powerrelated diagnostic information such as power (P), voltage (V), current(I), phase (Ø), and flux (f). Current systems do not have the ability tolook at the influence of the rotating machine (load) and its influenceon the motor.

b. Alignment Systems

The need to provide for precise alignment of the pump and driver sourcethrough a coupling means or intermediate gear box is well known. Anumber of suppliers exist for the systems to facilitate optimumalignment of the pump to power source. Such systems may includetraditional dial indicators, electronic position sensors and mostrecently laser alignment systems such as the ones manufactured by VibraAlign Inc. and Ludeca, Inc. These systems provide assistance to the pumptechnician for the installation or validation of proper motor and driveralignment with the pump. Many alignment systems provide an electronicoutput that can be displayed at the pump in the field.

c. Pump Diagnostic Systems

Pumps are one of the least reliable devices in a process plant. Theproper pump selection and application, installation, use and maintenancemust be assured for long life.

Pump manufacturers such as Gould Pumps commonly provide a pumpperformance curve with each pump. A pump curve is intended to assist auser in properly selecting the correct pump and pump impeller as well asto assist a user in operating a pump in the most efficient manner whileproducing the desired flow and pressure (head). Pumps are often usedwith constant speed power sources such as a 1800 RPM electric motor, orwith a variable speed drive (VSD) where the pump speed can be changed tovary the pump flow and head output. When pumps are used with variablespeed drives, distinct pump performance curves can be provided by themanufacturer at each desired speed. However, such curves are oftencalculated using the pump affinity law from the originally provided pumpcurve. The pump affinity laws are well known and are described inYedidiah, Centrifugal Pump User's Guidebook.

Several manufacturers use commercial personal computer systems for themeasurement and calculation of the pump performance curve at the factoryfor new or repaired pumps. These systems are sometimes used by pumpmanufacturers to calculate and provide the pump performance curves forthe end user. These systems may include sensors for determining pumpshaft speed (RPM), inlet and outlet pressures, outlet flow, shafthorsepower (brake horsepower) and fluid temperature. Standardalgorithms, such as those described by Yedidiah, author of CentrifugalPumps User's Guidebook, are applied to provide the pump performancecurve.

MARINTEK has undertaken work for the development of a knowledge-baseddiagnostics system called ROMEX, which is designed for rotatingmachines. The ROMEX system is a PC-based system which integrates datafrom commonly used condition monitoring systems and covers mechanicaland performance related faults with coverage of the rotating machinerotor, stator, coupler, bearing, blades, aerodynamics and combustionchamber for gas turbines. The ROMEX system does not use a pumpperformance curve as a method for diagnosing possible off-BEP operatingconditions or changes in the pump performance curve as a primary sourceof diagnostics for pump maintenance.

d. Pump Sensor Fusion

Recent published research from the Colorado School of Mines and theirSHARP system (System Health Assessment and Real-Time Prediction) suggestthat a diagnosis of pump health can be made via the fusion of physicalvariables such as pump inlet pressure, outlet pressure and flow inconjunction with a large artificial intelligence system made by Gensym.Artificial intelligence expert systems are used with some maintenancesystems and often involve hundreds and even thousands of rulesnecessitating a large and expensive computing workstation. The SHARPsystem does not use the pump performance curve as a primary source ofdiagnosis for pump maintenance.

e. Pump Field Diagnostics Systems

Ingersoll-Dresser Pump has a remote pump monitoring system tradenamedPumpTrac® which provides for the collection of vibration data, physicalprocess variables including pressure, flow, temperature and motoramperage. The monitoring systems provide for the trending and datalogging of input variables, an alarm mode for each variable and a phonemodem connection for alerting a plant operator of an alarm. The systemis able to provide pump variable monitoring for up to eight pumps.

Ingersoll-Dresser's PumpTrac Remote Pump Monitoring System has ahardened pump diagnostics system with I/O that displays local trendingdata of the input sensors, typically pump inlet and outlet pressures,process and gearbox oil temperatures, flow and vibration conditionmonitoring sensors. The display provides trend displays for eachvariable with the ability to display multiple windows so visualcorrelation of process variable trends with vibration can be made.

Further, the Ingersoll-Dresser system has the ability to set soft alarmpoints that can be actuated when an alarm point is exceeded. In oneoption, a soft alarm can actuate a traditional modem built into thesystem to call a predetermined number to indicate what variable has beenexceeded with data messages or a pre-recorded message.

The Ingersoll-Dresser device requires AC power and a dedicated telephoneline. The system is not networked with process industry standardprotocols and the use of AC power prevents certification to industryelectrical intrinsic safety standards.

The Ingersoll-Dresser PumpTrac system provides the variables needed toestablish a pump performance curve described in the present application,but does not provide the pump curve. However, the PumpTrac system doesnot provide for use of the secondary performance curves which provides abasis for root cause analysis of pump component failures, which isdescribed in the method herein.

f. Field Diagnostics Systems

Field diagnostics systems are known for air operated valves and motoroperated valves such as commercial systems available from Framatome,ABB, Liberty Technologies and Fisher Controls. There is no known fielddiagnostic for rotating equipment.

g. Point Diagnostics Devices

Several manufacturers provide sensors that can be applied to a pumpsystem for the partial determination of pump health. These sensors maymeasure the corrosion of the pump casing based on a thicknessmeasurement through ultrasonic thickness detection systems such as thosemanufactured by Stresstel, or by corrosion sensors such as thosemanufactured by Diagnetics. Similar portable monitoring devices, such asmanufactured by Vibrametrics, provide point measurements of pump casingcorrosion and thickness.

Pump and gearbox oil contamination and breakdown are commonly knownproblems with pump systems. In situ measurements of oil conditions canbe provided by devices such as the Digital Contamination Alert particlecounter provided by Diagnetics or through taking oil samples foroff-line laboratory analysis.

High bearing stress resulting from operation outside said design regimewill lead to bearing degradation. Bearing degradation can be detectedvia vibration monitoring. If degradation is severe enough, bearings willexhibit wear, which can be detected by oil sample analysis for wearparticles.

None of these techniques identify improper operation which results inequipment stress leading to progressive damage, and ultimately, failure.

h. Need For Root Cause Analysis Method and Apparatus

Consequently, there is needed a rotating equipment diagnostic method andapparatus that identifies the operating conditions which create damagingstress to said equipment.

Further, there is needed a diagnostic method and apparatus that iseffective in determining the root cause for bearing failure of rotatingequipment. Additionally, there is a need for a diagnostic method thatprovides guidance in the repair of a failing pump by supplying the rootcause analysis to an operator. By supplying root cause analysis to anoperator, the diagnostic method enables elimination of the cause offailure.

Further, a system that has the ability to look at the influence of aload from a rotating machine.

A system is further needed that uses a pump performance curve as amethod for diagnosing possible operating conditions outside of therecognized, recommended operating design regime or BEP.

Still further, there is a need for a system that does not require largeand expensive artificial intelligence computing workstations yet stillaccomplishes the forgoing function.

There is further a need for a second level of pump component diagnosisthat provides an ability to conduct root cause analysis of a pump orrotating equipment failure or an operating condition responsible for thefailure.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for a diagnostics system forrotating equipment commonly used in the process control industry. Alsoprovided is a method for diagnosing rotating equipment commonly used inthe factory and process control industry.

a. Apparatus

The system apparatus is intended to provide diagnostics of impendingfailure of turbines, compressors, fans, blowers, generators and pumps.The system can be effectively used for validating correct installationof a rotating machine and ancillary equipment attached to the machine.The system may also be used to diagnose change in the operatingcondition of a system for purposes of diagnosing maintenance and/ordiagnosing change in the operation and control of the system.Additionally, the system may be used to verify that maintenance wasproperly conducted through a validation of the performance signaturecurves on the newly installed equipment, and acquisition of equipmentbase line performance data for use with maintenance information systemsto provide a maintenance records audit trail. Further, the system may beused for continuous monitoring of rotating machine health and foradvising a control system operator of operation outside of a recommendeddesign regime or BEP operation to provide the opportunity to correct themachines operation conditions to BEP regime for reducing pump wear.

The apparatus can be applied to diagnose any rotating machine. However,the preferred embodiment of this apparatus is for the diagnosis of apump system.

Thus, the present invention is a rotating equipment or pump diagnosticssystem intended to provide field diagnosis of a rotating equipment orpump system, which includes rotating equipment, such as a pump and,optionally, rotating equipment or pump system ancillary components, suchas a coupler for connecting the rotating equipment to a driver source,or pump to a driver source or gear box and a driver source and a driversource controller. The driver source is typically an electric motor,diesel engine or turbine, and the driver source controller is typicallya motor control system or variable speed drive and measurement devicesfor key process and equipment monitoring variables.

The pump diagnostics method will be most frequently embedded in firmwareresident in a microcontroller in the pump diagnostics apparatus.

Four embodiments of the pump diagnosis apparatus are envisioned. Theembodiments will have a common set of core elements, with additionalelements provided to optimize the apparatus for its intended end use.

Apparatus Common Elements.

Elements common to all of the apparatus embodiments described include:

(a) sensors for process control variables and condition monitoring andInput/Output (I/O);

(b) A/D converters and signal conditioning appropriate to the type ofsensor;

(c) a microcontroller (μC) for providing signal reduction and executionof the method described in the Pump Diagnosis Method;

(d) an output device;

(e) memory for storage of tables, logging data, and storing the data andpump signatures resulting from the method;

(f) tables of pumped fluid properties, tables of rotating machinegeometry and installation dimensions; and

(g) a data input device.

The four embodiments of the apparatus include: (a) a portable, batterypowered field diagnostics apparatus; (b) a field-hardened, remotepowered, networked diagnostics apparatus; (c) a diagnostics apparatuswith controller; and (d) a diagnostic apparatus with host computer.

Portable Battery-Powered Field Diagnostics Apparatus.

The portable, battery powered field diagnostics apparatus preferably maybe a laptop computer, field hardened smart terminal, pen operatingsystem based terminal, or Apple Newton®, etc. The field diagnosticsapparatus preferably has sensors, I/O, A/D converters, a microcontrollerfor executing the required signal conditioning and method describedherein, memory, fluid property tables, rotating machine dimensional andperformance signatures, installation geometry tables, an input device(keypad) and a display and optionally a network connector. The primaryend use of this apparatus will be to guide field repair of a rotatingmachine and for validation of a successful repair and installation.

Field Hardened, Remote Powered Network Monitoring Apparatus.

The field hardened, continuously monitoring apparatus is comprised ofsensors, I/O, A/D converters, a microcontroller for executing themethod, a communication port for connecting the apparatus to a hostcomputer, memory, data logging, and communication capability for realtime acquisition and diagnosis of the rotating machine, and optionallyfor a remote display or host displaying the pump signatures.

The field hardened, remote powered, network monitoring apparatus may beeither a 2-wire powered apparatus, common to the process controlbusiness, a multi-wire communicating DC powered apparatus or an ACpowered communicating apparatus. A special embodiment of the fieldmounted apparatus will include the ability to power the apparatus andcommunicate with the apparatus over a standard 2-wire system with avariety of communication protocols. Examples of communication protocolsinclude HART, Foundation Fieldbus, PROFIBUS Pa., Ethernet TCP/IP andproprietary protocols such as Honeywell's Del., Yokogawa's Brain,Foxboro's Foxnet, etc.

The 2-wire embodiment includes a field hardened enclosure and is poweredwith a DC power supply used with 2-wire communication systems and iscapable of complying with industry standard (FM, CSA, CENELEC, etc.)safety requirements for intrinsic safety and explosion proofcertifications. The 2-wire apparatus has a subset of the totalfunctionality described due to a power limit (typically 10 volts and 4ma for HART and up to 50 ma and 9 volts for fieldbus) required by safetystandards.

A second embodiment of the field mounted and hardened apparatus is amulti-wire communicating apparatus. The multi-wire communicatingapparatus provides DC power at a higher power level than is used forintrinsic safety standards, but is in compliance with wire industrystandard protocols such as Modbus (RS232, RS485), Foundation FieldbusH2, Profibus FMS, Ethernet TCP/IP, ControlNet etc. In the multi-wirecommunicating apparatus embodiment, power is provided over one set ofwires from a remote power supply. Communication is provided over theremaining wires using industry standard protocols. This version of theapparatus typically will be safety certifiable only for “ExplosionProof” based on the design of the mechanical enclosure provided to housethe electronics.

An AC powered (120V or 220V) embodiment is also possible as is utilizedin Ingersoll-Dresser Pump's Remote Pump Monitoring System, trademarkedPumpTrac (1995).

Diagnostics Apparatus with Process Controller.

A third embodiment of the apparatus is a controller typically found inprocess plants. Typical controllers that could be used with modificationfor a rotating machine apparatus diagnosis include: motor controllersfound in motor control centers used to control motor/pump systems,variable speed drive controllers, DCS system controllers, programmablelogic controllers (PLC's), compressor or turbine control systems, singleor multiloop controllers, etc.

Diagnostic Apparatus—Host Computer.

A fourth embodiment of the apparatus is a host computer typically usedfor maintenance information systems. The apparatus includes sensors ordata from sensors gathered from a database (data historian from adigital control system), I/O and AID converters as appropriate, amicroprocessor with the pump diagnostics method, a database for storingpump diagnostic results, alarm and alert management system,communications for networking with other host computers, such as DCS, amaintenance engineer's PC via an Ethernet TCP/IP network, the Internet,or the plant information management (IS) system network.

b. Method.

The method of the present invention may be used to assist a maintenanceengineer in the diagnosis of rotating equipment including turbines,compressors, fans, blowers and pumps. The preferred embodiment is amethod for diagnosing pumps of all types; constant head pumps such aspositive displacement or reciprocating pumps and in particular, variablehead centrifugal pumps.

The method is based on the use of the pump performance curve as thebasis for determining the degradation of the pump due to off designoperation; fluid damage from erosion, cavitation and recirculation; andthrough normal wear and tear.

The primary “pump performance curve” and pump “head curve” is well knownin the industry and for purposes of this patent will include therelationships between the dependent head or pressure and the independentvariable, flow. This relationships are traditionally plotted on a graph,with the dependent pump performance variables plotted on the ordinateand flow, the independent variable plotted on the abscissa.

Additional variables may also be plotted versus flow, and for purposesof this method will be described as “secondary performance curves”. Forpurposes of this patent, “secondary performance curves” will include,but are not limited to the relationships between the dependent pumpperformance variables, net positive suction head, brake horsepower, pumpefficiency, thrust bearing force, radial bearing force, motor torque,pump specific speed, dynamic pressure, net positive suction headavailable, etc. all plotted vs flow, the independent variable. Thesesecondary curves provide a basis for root cause analysis of pumpcomponent failures.

The method is based on a comparison of the current pump signature curvesand operating point resulting from the acquisition of process variablesfrom sensors that measure a current condition of the rotating equipmentor pump, and the original data in the form of an original or previouspump performance signature curves from prior monitoring, and knowledgeof the rotating equipment or pump geometry, installation and pipinggeometry, ancillary equipment knowledge and geometry, and properties ofthe pumped fluid. This diagnostics method can be applied to any rotatingmachine, but the method for pumps is described herein. The diagnosticsmethod can be used in conjunction with an apparatus that provides forthe acquisition of the required variables, the computation of therequired pump signatures, operating points and curves, the display ofcomputed variables, a logic element for deducing and diagnosing the pumpby component, and optionally, a communication to a host computer.

The computing apparatus may be a portable, battery-powered fieldhardened PC with I/O for use in field diagnosis of the rotating machine,or a field mounted continuously monitoring apparatus with data I/O,logging, and communication capability for real time acquisition anddiagnosis of the rotating machine, and optionally displaying the pumpsignatures on a remote display or host. The computing apparatus may alsotake the form of a host with I/O and a means of executing the claimedmethod. Hosts capable of using this method include a compressor orturbine control system, a maintenance information system, a personalcomputer, supervisory control and data acquisition system (SCADA) or atraditional process control system. The method may also be implementedin a motor controller or a PLC often used in a motor control center forthe motor used to drive the pump.

The apparatus may also be used with more than one rotating machine orpumps through the multiplexing or networking of the sensors frommultiple pumps.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representation of a rotating machine and motor system.

FIG. 1b is a cross sectional view of the pump.

FIG. 2 is a schematic of diagnostic apparatus of the present invention.

FIG. 3 is a schematic of a field hardened remote embodiment of theinvention.

FIG. 3a is a field hardened remote embodiment of the invention.

FIG. 4a is a pump diagnostic apparatus using a programmable logiccontroller (PLC) as a platform.

FIG. 4b is a pump diagnostic apparatus using a host computer as aplatform.

FIG. 5 is a typical pump performance curve.

FIG. 6 is an original performance curve.

FIG. 6a is a pump performance curve at operating point.

FIG. 6b is a pump performance curve with operating point below BEPperformance shifted downward.

FIG. 7a is a typical dynamic pressure sensor spectra.

FIG. 7b is a typical velocity and acceleration vibration spectra.

FIG. 7c is a NPSH_(Avail) v. NPSH_(Req'd) graph.

FIG. 7d is an H v Q curve illustrating a “droop” condition.

FIG. 8 is a graphical representation of spectra of same vibration sourceobtained from different types of transducers.

FIG. 9 is a graphical representation of data pump secondary performancecurves.

FIG. 9a is a graphical representation of centrifugal pump secondaryperformance curves.

FIG. 9b is a graphical representation of positive displacement pumpsecondary performance curves.

FIG. 9c is a graphical representation of centrifugal dynamic pressurecurves.

FIG. 10 is a flow chart representing one embodiment of the method of theinvention.

FIGS. 11 through 41 are additional flow charts representing embodimentsof the method of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

a. Apparatus

Referring to FIG. 1, shown is a rotating machine and motor systemdesignated generally 10. It should be understood that the apparatus fordiagnosing a rotating machine and motor system may be used to diagnoserotating equipment including pumps, turbines, fans, blowers, compressorsor other types of equipment. A pump and motor system is shown in FIG. 1for purposes of example only. Pump and motor system 10 includes motor 12and a rotating machine or rotating equipment, such as pump 14. Motor 12may be an electric motor, diesel engine or turbine, or other powersource. Motor 12 is operatively connected to rotating equipment 14 viacoupler 16. Rotating equipment 14 has inlet 18 and outlet 20. Downstreamfrom outlet 20 of rotating equipment 14 is typically provided a finalcontrol element, such as control valve 22.

The diagnostic apparatus for one embodiment of the invention isdesignated generally 24 (FIG. 2). The system can be used effectivelyused for:

a) validation of correct installation of pump 14 and ancillary equipmentattached to pump 14;

b) diagnosis of change in an operating condition of pump and motorsystem 10 for purposes of maintenance and for changing the operation andcontrol of pump and motor system 10;

c) verification that maintenance was properly conducted through avalidation of the correct dynamic performance of the repaired equipment;and

d) collection of equipment base line or original performance data foruse with maintenance information systems to provide an audit trail ofmaintenance records.

Diagnostics apparatus 24 can be applied to any rotating equipment.However, the preferred embodiment of this apparatus is the diagnosis ofthe centrifugal pump. Diagnostic apparatus 24 includes process sensorsfor measuring process conditions and for generating process variables,which are key to determining a change or degradation of performance ofpump and motor system 10. Sensors, including process sensors, maycommunicate variables and diagnostics parameters via a networkconnection to a host computer including digital control systems (DCS's)such as the Foxboro I/A®, supervisory control and data acquisition(SCADA) systems such as that provided by the Intellution Fix®, or amaintenance information system such as that provided by the SAP for thepurpose of providing predictive and preventative maintenanceinformation. Process sensors may include outlet pressure sensor 26,shown in FIG. 1, which is positioned proximate outlet 20 of pump 14, fordetermining pump outlet pressure. Process sensors may also includeflowmeter 28 for determining a flow rate of product downstream ofrotating machine 14, or other sensors for monitoring process conditions.

Further examples of process sensors include temperature sensing device30, which is approximately positioned upstream or downstream of rotatingmachine 14 for determining temperature of a process fluid; inletpressure sensor 32, which is positioned proximate rotating equipmentinlet 18 of rotating machine 14 for determining rotating machine inletpressure; and valve position sensor 34. Valve position sensor 34 ispreferably mounted on control valve 22 and communicates withinput/output device 36 for converting electrical signals to digitalsignals. Valve position sensor 34 is provided to determine the positionof a control valve or shaft. Additionally, valve position sensor 34provides input for a method to calculating flow through pump or rotatingequipment 14. The flow through valve 22 can be calculated from the valveposition, the pressure drop across the valve and known fluid propertiesand geometry from the valve supplier. The flow through valve 22 may thenbe and stored as original data. This information enables a baseline headvs. flow (H v Q) performance reference curve to be developed in theabsence of a flowmeter. Additionally, knowledge of valve positionprovided by valve position sensor 34 is used to alert possibledeadheading of pump or rotating equipment 14.

Input/output device 36 of diagnostic apparatus 24 communicates withprocess sensors for receiving process variables therefrom. Input/outputdevice 36 transmits process variables received from process sensors tocomputing device 38.

The computing apparatus may be:

a) a portable, battery powered field hardened PC with I/O for use infield diagnosis of the rotating machine, shown in FIG. 2, or

b) a field mounted continuously monitoring apparatus, shownschematically in FIG. 3, with data I/O, logging, and communicationcapability for real time acquisition and diagnosis of the rotatingmachine, and optionally displaying the pump signatures on a remotedisplay or host, shown in system with a remote host in FIG. 3a, or

c) a host with I/O shown in FIG. 4b and a means of executing the methoddescribed herein. Hosts capable of using this method include acompressor or turbine control system, a programmable logic controller(PLC), a maintenance information system, a personal computer,supervisory control and data acquisition system (SCADA) or a traditionalprocess control system, or

d) the method may be implemented in a motor controller or a PLC, shownin FIG. 4a, often used in a motor control center for the motor used todrive the pump.

FIG. 2 is a schematic of diagnostic apparatus 24. Box 40 represents pumpand motor system 10. Data is shown being transmitted from pump and motorsystem box 40, as represented by a plurality of arrows generallydesignated 42. Examples of data being transmitted include processvariables generated by process sensors and condition monitoringvariables generated by machine sensors, to be discussed below. Data istransmitted to a sensor excitation and conversion device, represented bybox 44. Converted data signals are then transmitted from sensorexcitation and conversion device 44 to signal multiplexers, representedby box 46. Alternately, the sensor inputs may be inputted directly tothe A/D converter shown in box 52.

Sensor data may be multiplexed to microprocessor 48 to provide forasynchronous measurement of selected inputs which are not time criticalor do not need to be sampled continuously. Converted data transmitted bysensor excitation and conversion device 44 to signal multiplexers 46 isrepresented by arrows, designated generally 50. From signal multiplexers46, data is then preferably transmitted to an A/D converter, such asthose manufactured by Analog Devices and Crystal Semiconductor,represented by box 52. Examples of microprocessor 48 include Motorola's16-bit 68 HC16 or 32-bit LC302. D/A converter, represented by box 54, isprovided in the preferred embodiment so that microprocessor 48 maycommunicate with the pump and motor system, represented by box 40.Diagnostic apparatus 24 may also include a real time clock 59 withoptional battery backup that can be used to time stamp data acquiredsynchronously or asynchronously. Real time data may be alternativelyacquired via the network 115 from a host computer as is provided withFoundation Fieldbus or Ethernet networking technology.

In the preferred embodiment, microprocessor 48 is in communication withmemory storage 56, co-processor 58, and a disk drive or other datastorage or retrieval means 60. Co-processor 58 is optional. Examples ofa suitable co-processor include Texas Instrument's DSP microcontroller,with embedded frequency analysis algorithms such as fast fouriertransform (FFT) or wavelets. Co-processor 58 may be provided to processspectral data from sensors such as accelerometers. The co-processor isused to off load microprocessor 48. Additionally, diagnostic apparatus24 may be provided with the following: an A/C power supply receivingdevice 62, as is commonly known in the art; charger 64; battery 66;power supply 68, commonly known in the art; communication receivingdevice 70; keypad 72; keyboard 74; and an output device, such as printer76 and CRT display 78.

In the preferred operation of diagnostic apparatus 24, microcomputingdevice 48 receives data 42 from input/output device 36 and stores datain memory storage 56. To establish an original condition, original datamust be entered into memory storage 56. For purposes of thisapplication, original data includes tables of machine geometry, machineinstallation parameters, ancillary equipment parameters originalperformance curves and fluid properties of the pumped product, as wellas previous condition data. Previous condition data refers to datagathered in a previous set of measurements that is stored for retrievaland comparison purposes. Therefore, measured data, including processvariables and condition monitoring variables, may be compared tooriginal data to determine performance deterioration of rotating machineand motor system 10. Microprocessor device 48 of diagnostic apparatus 24compares measured data with original data for generating an output viaprinter 76, CRT display 78 or other output devices based on thecomparison.

Referring again to FIG. 1, in the preferred embodiment diagnosticapparatus further comprises machine sensors for generating conditionmonitoring variables. Machine sensors allow data to be gathered fromindividual components for determining specific problems with pump andmotor system 10. Computing device 38 is used to compare conditionmonitoring variables with stored original data for diagnosing rotatingequipment degradation and for generating an output based upon thatcomparison. A discussion of various types of machine sensors follows.

Machine sensors may include rotating equipment vibration sensor 80,which is preferably mounted on rotating equipment 14 for determiningvibration of rotating equipment 14. Vibration sensor 80 is incommunication with input/output device 36 for providing conditionmonitoring variables to computing device 38. A further machine sensor isdynamic pressure sensor 82, which is positioned in the product fluidstream downstream from rotating equipment outlet 20 or positioned withinrotating equipment casing 84 of rotating equipment 14 and is in contactwith the process fluid.

Diagnostic apparatus 24 (FIG. 2) may include additional machine sensors,including motor vibration sensor 86, which is preferably mountedproximate a bearing for determining bearing vibration. Motor vibrationsensor 86 is preferably in communication with input/output device 36 forproviding condition monitoring variables thereto.

By receiving data from gearbox vibration sensor 88, which is mountedproximate gearbox 87 of rotating equipment 14, and from motor supplysensor 90, which senses motor current and motor voltage, and fromalignment sensor 92, diagnostic apparatus 24 may diagnose whetherrotating equipment 14 requires impending maintenance.

Diagnostic apparatus 24 may also include rotating machine seal leakagedetector or sensor 94. Seal leakage sensor 94 is mounted proximate ashaft seal on rotating machine 14 for detecting seal leakage. Sealleakage sensor 94 provides condition monitoring variables toinput/output device 36 for providing computing device 38 with conditionmonitoring variables.

Diagnostic apparatus 24 may include additional machine sensors, such asoil contamination sensor 96. Oil contamination sensor 96 is preferablymounted in gearbox 87 or on an oil sump for detecting oil contamination.Oil contamination sensor 96 provides condition monitoring variables toinput/output device 36 for providing computing device 38 with conditionmonitoring variables.

Additional machine sensors, such as viscosity degradation sensor 98, mayalso be provided. Viscosity degradation sensor 98 is preferably mountedproximate a gearbox for detecting oil viscosity degradation. Oilviscosity degradation sensor 98 is for providing computing device 38with an oil condition monitoring variable.

Additional machine sensors include torque sensor 100, which ispreferably mounted proximate to the shaft of rotating machine 14. Torquesensor 100 is in communication with input/output device 36 for providingcomputing device 38 with torque data. Machine sensors may also includeangular velocity sensor 102, preferably mounted proximate to shaft ofrotating machine 14. Angular velocity sensor 102 is in communicationwith input/output device 36 for providing computing device 38 withangular velocity data for computing input power to rotating machine 14and computing the output fluid power of rotating machine 14 and theefficiency of rotating machine 14.

Additional machine sensors include corrosion sensor 104. Preferably,corrosion sensor 104 is mounted on rotating machine casing 84 formeasuring degradation of rotating machine casing 84 resulting fromundesirable conditions, such as corrosion, pump cavitation or erosion.Corrosion sensor 104 is preferably in communication with input/outputdevice 36 for providing condition monitoring variables thereto. Atypical corrosion sensor uses electrical potential generated bycorrosion to provide a voltage measurement. Corrosion sensor 104 can belocated anywhere in rotating equipment 14 of pump and motor system 10where high corrosion is expected, e.g., a thin section or areas of highflow.

Further machine sensors include ultrasonic thickness sensor 106.Ultra-sonic thickness sensor 106 is preferably mounted on rotatingmachine casing 84 for measuring degradation of rotating machine casing84 from undesirable conditions such as corrosion, pump cavitation orerosion. Ultrasonic thickness sensor 106 is preferably in communicationwith input/output device 36 for providing condition monitoring variablesthereto.

Additional machine sensors include accelerometer 108, bearingtemperature sensor 110, bearing vibration sensor 112, and axialdisplacement sensor 113.

Diagnostic apparatus 24 may be configured in one of two classes. In afirst class, embedded systems, such as microcontrollers, containsoftware that is burned into the chip's logic, i.e., firmware. Theembedded system provides a software instruction set which is permanent.Embedded systems are used in a field hardened embodiment of diagnosticapparatus 24, discussed below.

Another form of the embedded system embodiment uses downloadableexecutable code in electrically alterable memory such as EEPROM or FLASHfor equipment identification numbers, specific flow data—fluidparameters, pump performance curves, etc.

A second class of diagnostic apparatus comprises a real time computingplatform. Configurable logic will normally be remotely located in acomputing host. Examples include personal computers, workstations, PLC,DCS, and minicomputers. A secondary form of this real time computingplatform is a portable real time computing platform. A portablecomputing device allows testing to be performed near pump and motorsystem 10, thereby allowing for observation of the equipment. In oneembodiment of the invention, diagnostics apparatus 114, FIG. 3, operatesvia a bus wherein there exists no central controller. Such a system isprovided with the enhanced digital HART protocol, proprietary protocols,such as Honeywell's Del., Yokogawa's Brain, proprietary protocols asprovided by Bailey and Foxboro for their field instruments, and emergingfield buses such as Foundation Fieldbus, Profibus, or World FIP,Ethernet, etc.

In a more fully featured embodiment shown in FIG. 3a, the diagnosticapparatus 24 is powered by and communicates over a multi-wire network,such as a three-wire network in which DC power 117 is remotely providedover a separate set of wires or a four-wire network in which DC power isremotely provided over a separate set of wires. Protocols typically usedinclude Modbus (RS232 and RS485), Foundation Fieldbus H2, Profibus H2,and Ethernet, I/P, TCP/IP, UDP/IP, etc.

In one embodiment of the invention, shown in FIG. 1, machine sensors areintegrated with input/output device 36 and computing device 38 forcomparing measured performance signatures of rotating machine 14 at asecond time with an original condition signature at a first time fordiagnosing degradation of rotating machine performance. In the preferredembodiment, process sensors and machine sensors are electricallyisolated from the apparatus. Comment: Electrical isolation is wellknown. It is accomplished with transformers or optically withOPTO/couplers.

In another embodiment of the invention, shown in FIG. 4a, a PLC is usedas the diagnostic apparatus platform, and the PLC's microcontroller 188,which is positioned proximate rotating machine 14 for controllingrotating machine 14. For example, microcontroller 188 may controlrotating machine 14 by issuing a control set point to control valve 22,I/P 35. Preferably, microcontroller 188 possesses firmware for providinginstructions to rotating machine 14.

A further embodiment of the invention, shown in FIG. 3a, provides thatfield hardened computing device 114 of diagnostic apparatus 24 ispositioned proximate rotating machine 14 and that computing device 114provides a control signed to the control valve 22 or variable speeddrive. By providing that diagnostic apparatus 114 controls the processas a hardware platform, one benefit is the ability to utilize acombination of known condition monitoring variables, e.g., vibrationvariables from machine sensors, with process variables from processsensors. Process sensors provide information about the performance ofpump and motor system 10. Machine sensors provide knowledge of thehealth of rotating equipment and motor system 10. Examples of machinesensors that provide vibration variables include motor vibration sensor86 or bearing vibration sensor 112. When known condition monitoringvariables and process variables are combined, decisions can be madethrough logical deduction about the condition of pump and motor system10, the process and the ability of pump and motor 10 to provide itsintended function.

Referring now to FIG. 3, a field hardened remote embodiment of theinvention is shown. Field hardened computing device, designatedgenerally 114, of diagnostic apparatus 24 is designed to be positionedproximate rotating machine 14.

Field hardened, networked diagnostic apparatus 114 may be used withpumps using standard communication protocols used in the process controland factory automation industries.

Preferably, field hardened apparatus 114 is configured to downloadexecutable code specific to a particular rotating machine 14 foroperating rotating machine 14. Field hardened remote embodiment 114 ispreferably encased in field hardened enclosure 116, is remote-powered,and is a networked. In a preferred embodiment, field hardened computingdevice 114 has digital communications with a network 146 and serves bothas a publisher and a subscriber of data over the network. Preferably,field hardened computing device 114 is powered by a remote power supply115, shown in FIG. 3a. The field hardened embodiment is preferablydesigned for operation in inclement environments without additionalprotection. The device may be mounted on or proximate to the pump orother rotating machine 14 and should be designed to withstand highhumidity, extreme temperatures, high EMF (electrical noise), rain andsnow and other harsh environmental conditions. Additionally, fieldhardened apparatus 114 should be provided with explosion-proofprotection, i.e., be designed not to cause a spark or explosion inhazardous gases. Such an apparatus may be powered by and communicateover a two-wire loop.

The process control industry routinely uses field-hardened sensors,actuators, and instruments that are remotely powered with a DC powersupply 115 (typically 12-24 V) over a twisted shielded pair of wires.Communication is also provided in a full duplex fashion with processindustry protocols to and from the field device from host computers suchas a PLC or DCS.

Field hardened apparatus 114 is preferably capable of satisfyinginternational safety standards for electronic apparatus such as FM, SAA,JIS, CENELEC, and CSA two-wire intrinsic safety and explosion proofdevices. Field hardened enclosure 116 is also preferably moisture proof(NEMA 4) and capable of achieving IEC CE mark requirements for heavyindustry electrical field mounted instruments. Intrinsic safetystandards limit the available power to the field device to avoidignition of hazardous or flammable gases that may be in the area nearthe device. Use of low power consumption electronics andmicrocontrollers is essential to meet these safety requirements.

Field hardened apparatus 114, shown in FIG. 3, is encased in fieldhardened enclosure 116, and receives data from process and machinesensors, designated generally 118. Data received from process andmachine sensors 118 is represented by arrows designated generally 120,and is transmitted to I/O, 121 and then to an excitation and conversiondevice, represented by box 122. Converted data signals are thenpreferably transmitted from sensor excitation and conversion device 122to signal multiplexers, represented by box 124. Converted data is thenpreferably transmitted to an A/D converter, represented by box 126,which communicates with microcontroller 128. Conditioned sensor datasignals may be optionally transmitted directly to an A/D converter 126without use of the multiplexer 124. Microcontroller 128 is preferably incommunication with co-processor 130, which has the ability to time-stampdata received. ROM 127 communicates with A/D converter 126,microcontroller 128 and co-processor 130 for providing instructions.Time-stamping of data is facilitated by an optional real time clock 132.Additionally, microcontroller 128 is in communication with electricallyalternatable memory 134 for acquisition of pump system, fluid property,pump signature data. Communications device 136 is in communication withmicrocontroller 128 for transmitting information to a network. Finally,in the preferred embodiment, field hardened apparatus 114 is providedwith display 138 so that an operator can get information from the devicein the field. An optional communication port 146 permits data transferfrom handheld vibration monitors 142 or pump diagnostic subsystems 150.

Referring now to FIG. 4a, an additional embodiment of diagnosticapparatus 24 uses a programmable logic controller (PLC) 240 as aplatform. Programmable logic controllers are commonly used for controlin factory and process control applications and are frequently used formotor control in motor control centers. PLCs by construction provideI/O, the ability to power sensors and actuators through the I/O, A/Dconverters and a microcontroller with configurable logic algorithms.PLCs also have communication interfaces 190 with standard processcontrol protocols as well as support for remote PC hosts and printers.PLC logic is often configured using a HMI 194 such as those provided byS-S Technologies as well as PLC manufacturers such as Allen Bradley orSiemens. The PLC has all of the necessary elements for implementing thedisclosed diagnostic method.

The shortcomings of a PLC implementation include the inability to obtainintrinsic safety (two-wire) approvals due to the high power consumptionof a PLC and the need to house a PLC in a Division II, shelteredenvironment. The PLC does, however, provide an ideal platform for thediagnostics method as it is a cost effective package for the necessaryelements and has the ability to provide the logic configuration neededfor the pump diagnostics method. Further, the diagnostics method runningon the PLC can provide the diagnostics alerts 154 for off-BEP operationof a pump so that operator could provide immediate corrective controlaction to operate the pump in a BEP regime through a change in thecontrol set point.

In this embodiment, shown in FIG. 4a, diagnostic apparatus 240 uses aPLC platform for providing sensor I/O, A/D conversion and signalconditioning. The PLC platform additionally provides microcontroller 188and method logical elements that are embedded in firmware resident inthe PLC's microcontroller 188. This embodiment further includes a PLCoutput 192 and communication network port 190.

Additionally, this embodiment of diagnostic apparatus 240 may furtherinclude logic configurator 194 for establishing pump method logic in PLClanguage and for downloading pump logic into PLC microcontroller 188.Examples of logic include ladder logic, sequence charts, functionblocks, etc. The apparatus may further include a function block withsensor inputs, outputs, alerts and the pump method.

A further embodiment of diagnostic apparatus 240, shown in FIG. 4b,wherein a host computer 236 is used as the platform. A host computer ismost often used for maintenance information or maintenance systems, butmay also be the DCS control system. The apparatus will include sensorsor data from sensors gathered through from a database (data historianfrom a digital control system) 210, I/O 228 and A/D converters asappropriate 238, a microprocessor with the pump diagnostics method, adatabase for storing pump diagnostic results 210, alarm and alertmanagement system, communications 212 for networking with other hostcomputers 256, such as DCS, maintenance engineer's PC via an EthernetTCP/IP network, the Internet, or the plant information management (IS)system network.

The host computer embodiment of diagnostic apparatus 240 acquires sensorinput via point-to-point or multidrop wired sensors or transmitters suchas 32, 28, 26, and 30, wired to I/O 228, which provide conversion andnetworks digital sensor data via a bus to the microprocessor based host.Sensor data may be alternatively gathered via a bussed sensor network230 commonly called fieldbus.

Commercial workstations, PCs, and servers like the IBM 400 are thepreferred computing platforms for maintenance information systems. I/Ointerfaces with appropriate A/D converters and signal conditioning whichconvert the required sensors (physical and condition monitoring) todigital data are readily available from companies like GE Fanuc andNational Instruments. The maintenance information system can processsensor inputs using diagnostics methods within the workstation or PCmicroprocessor. Plug-in communication output boards are readilyavailable from National Instruments for the many process communicationprotocols, and can be readily networked with the DCS or maintenanceengineer's PC with Ethernet TCP/IP based network protocols.

Host computers are able to share data over a network connection throughthe use and support of standard data sharing network services such asthose provided by Microsoft's Windows environment through OLE, OPC,JAVA, netDDE, DDE and to databases through standard database serviceslike ODBC, OLEDB, SQLSERVER, etc.

In the host computer platform embodiment, shown in FIG. 4b, thediagnostic apparatus 236 may further include sensors wired to a centralinput/output 228, A/D card 238 with sensor signal conditioning, a cardconnection to an input/output network, sensor input/output network 240,such as a DCS data highway, computer 236, such as a PC DCS workstation,etc., that includes data input bus 240, computing element, memory, inputdevice, such as a keyboard, network communications, a display 224, datastorage 210, real time clock, and a software-based implementation of thepump method.

Diagnostic apparatus 236 preferably includes an alert device thatresponds to a condition of rotating equipment 14. An alert istransmitted to a host computer 256 via the network 212.

Apparatus may further include network services, such as OLE, OPC, NetDDE, or ODBC, for publishing pump data and alerts with softwareapplications resident on the computer.

In the preferred embodiment, shown in FIG. 3a, diagnostic apparatus 114possesses communication port 70 for importing condition monitoringvariables from portable hand-held data logging device 142. Examples ofdata logging devices include hand-held vibration monitoring systems, oilanalysis devices, corrosion and ultra-sonic thickness gauges, etc.Preferably, portable hand-held data logging device 142 possess adatabase for storing the input devices. Additionally, portable hand-helddata logging devices 142 may use an intelligent network device.

Diagnostic apparatus 114 may additionally possess process communicationport 70 for communicating with intelligent network devices. Examplesinclude Hart, Foundation Fieldbus, Profibus, Modbus, Ethernet TCP/IP,etc. An example of an intelligent network device for communicating withprocess variable digital bus 70 includes a control valve position sensor34, shown in FIG. 3a.

Diagnostic apparatus 114 may further include monitoring system digitalbus 146 for communicating with intelligent network devices havingcomputing engines for collecting condition monitoring variables.

In one embodiment of the invention, diagnostic apparatus 114 includescondition monitoring subsystems 150 for rotating machine 14. Theapparatus can serve to collect data from other smart diagnosticssubsystems such as a smart motor and provide a database for the entirerotating equipment system over a network for analysis by others with amaintenance information system, expert system, control system or SCADAsystem. Condition monitoring subsystems 150 are interfaced withcomputing device 114 via standard communication network interfaces fortransmitting subsystem data over a standard communication network.Examples of condition monitoring subsystems include a Bentley NevadaTrendmaster 2000, a smart motor, and gearbox condition monitoring systemand Fisher Controls Fieldvue® valve diagnostics system. A Bentley Nevadasystem is primarily used with compressors and steam turbines fordetermining vibration and uses a proximity sensor positioned near ashaft for determining eccentricity or orbit of the shaft in the bearing.

In a further embodiment of the invention, diagnostic apparatus 114comprises external processed data storage device 152 for storingsubsystem data. The storage of subsystem data is necessary whendiagnostic apparatus 114 is a network client having a memory databasefor storing data from a network rotating machine subsystem. In thisembodiment, subsystem data is stored as a substitute for direct sensoror pump subsystem component condition monitoring inputs. If any othersubsystem is analyzed, then data must be stored. Otherwise, diagnosticapparatus 114 must include its own sensors. One reason that subsystemdata must be stored is that a subsystem may already have a fast fouriertransform (FFT). Therefore, this embodiment of diagnostic apparatus 114must treat data differently since information has already beenpreprocessed.

In the embodiment of the invention, schematic FIG. 3 shows co-processor158 of diagnostic apparatus 114 is in communication with microcontroller128 for providing spectral signal reduction of condition monitoringvariables from the frequency domain sensors 118. These include pumpvibration sensor 80, motor vibration sensor 110, dynamic pressure sensor82, and bearing vibration sensor 112, shown in FIG. 1.

Further examining the diagnostic apparatus schematic, FIG. 3, diagnosticapparatus 114 is preferably provided with alert device 154 forindicating when undesirable equipment conditions occur. Undesirableequipment conditions are determined by comparing process or equipmentconditions with user configured levels for sensor-computed variables orhigh limits. Examples of undesirable equipment conditions includevibration levels that exceed the manufacturer's recommended amplitudelevels.

In one embodiment, when an alert indicates an undesirable equipmentcondition, an optional contact closure 156 is provided to shut down pumpand motor system. Contact closure 156 is located in diagnostic apparatus114 to switch voltage or current to provide an alert or safe equipmentoperation. For example, in one embodiment, contact closure 156 is always“ON” and disconnects when an alert is generated. Conversely, contactclosure 156 may default to the “OFF” position and connect when an alertis generated. Other uses for contact closures include lighting a warninglight, disconnecting a motor, reducing power to a motor, etc. If avariable speed drive motor is utilized, contact closure 156 can belocated proximate the motor or may be positioned in a control room. Thecombination of contact closure 156 with diagnostics results in improvedcontrol of the pump and motor system 10.

FIG. 3a shows field hardened apparatus 114, in a process control systemconnected to an host computer, 236, typically a DCS system.

Diagnostic apparatus 114 may additionally include a final controlelement, such as control valve 22 whereby the final control element isresponsive to the output communication 70 generated by computing device38 for operating pump 14 and motor system 12 in a recommended operatingdesign regime. A final control element is typically used to control flowthrough pump 14 to meet piping and process system requirements, and maybe used to conduct tests required to generate a performance curve.Closing control valve 22 by providing an output signal to the valve I/P35 increases resistance and causes rotating equipment or pump 14 tooperate at a higher pressure and a lower flow rate. Similarly, openingcontrol valve 22 results in reduced system resistance, increased flowand lowering pressure.

Another example of a final control element is a variable speed driveconnected to the pump which may be used as a controller. A variablespeed drive works to provide a required flow and pressure demand byadjusting the speed of the rotating equipment 14.

FIG. 3 shows diagnostic apparatus 114 includes, in the preferredembodiment, optional real time clock 132 in communication with computingdevice 128, for time stamping process variables and original data fortime-based comparisons.

Diagnostic apparatus 114 may further comprise a display for displaying aperformance signature at a first time and at a second time.

In an additional embodiment shown in FIG. 2, diagnostic apparatus 24 isa portable battery-powered field apparatus. In this embodiment,diagnostic apparatus 24 further includes co-processor 58 which containsa software resident spectral analysis engine 158. Spectral analysisengine 158 is for processing signals from frequency domain sensors.Frequency domain sensors include rotating equipment vibration sensor 80and dynamic pressure sensor 82, as well as motor vibration sensor 110and bearing vibration sensor 112. Co-processor 58 receives data frommicroprocessor 48 or directly from frequency domain sensors.

Diagnostic apparatus 24 may also include a network communication port160. Network communication port 160 is for communication with portablevibration monitor 142 for communicating output from computing device 48to a network 115, and communication device 70 for communicating datafrom computing device 48 to a networked host.

b. Method

The method of practicing the invention enables diagnosis of rotatingequipment commonly used in the factory and process control industry. Themethod is intended to be used to assist a maintenance engineer in thediagnosis of turbines, compressors, fans, blowers and pumps. Thepreferred embodiment is a method for diagnosing pumps, particularlycentrifugal pumps.

The method of the invention is based on a comparison of measured pumpsignature curves resulting from the acquisition of process variablesfrom sensors monitoring a current condition of the pump and the originalor previous pump performance curve from prior monitoring or knowledge ofpump geometry, installation data, ancillary equipment data andproperties of pumped process liquid.

The diagnostics method can be used in conjunction with diagnosticapparatus 24, shown in FIG. 2, apparatus 114 shown in FIGS. 3 and 3a,PLC apparatus shown in FIG. 4a or PC host 236 shown in FIG. 4b, whichprovides for the acquisition of process and condition monitoringvariables, the computation of the required pump signatures and curves,the display of the computed curves, a logic element for deducing anddiagnosing the pump by component, and optionally a communication to ahost computer.

The method of the invention identifies and interprets changes in theperformance curve, or pump performance curve, by monitoring andanalyzing key pump conditions. Typical pump performance curves are shownin FIG. 5. Changes in the pump performance curve may be used to diagnosea root cause of pump component failures. The diagnosis is beneficial infailure prognosis, maintenance planning, changing the operatingcondition of the pump to avoid damage and is often used with a companionhost system.

The centrifugal pump performance curve in FIG. 6 is provided by a pumpmanufacturer based on a standard test described by the HydraulicsInstitute, the recognized standards authority for the pump industry. Thepump performance curve is routinely used by the end user to properlyselect the appropriate pump and impeller to provide the desired fluidflow or head condition.

Changes to the pump performance result from the use, wear,misapplication and operation of the pump outside the design conditions.These changes alter the pump performance curve. These changes can beused as the first step in diagnosing: 1) root cause analysis of failingpump components; 2) incorrect pump application or installation; 3) pumpoperation at flow/pressure conditions different than original design(BEP).

The method of the invention uses the pump performance curve to identifypossible problems, which are often due to pump misapplication or failingcomponents. Misapplication problems are diagnosed by comparing themeasured operating conditions with the BEP region or recommendedoperating design regime of the pump performance curve. Misapplicationresults in operation outside the recommended operating regime, leadingto pump stress, wear and failure.

Pumps are designed by the manufacturer to operate at the best efficiencypoint (BEP) or recommended operating design regime. The highestreliability occurs at the best efficiency point of the pump. Pumpdesigns preferably minimize radial and thrust bearing loads, vibrationlevels, preclude recirculation or cavitation, and provide for the bestconversion of mechanical energy to fluid energy at the BEP. Operation atconditions different from the BEP (off-BEP) can result in rapiddeterioration of the pump. The diagnosis of off-BEP operation canfacilitate pump component failure analysis. If diagnostic information iscommunicated to a control system, adjustments to pump operation foroperating closer to the BEP increases pump life.

The method of the invention utilizes the full range, at all operatingconditions, of pump performance curves. The pump operating variables ofhead, pump efficiency, brake horsepower, net positive suction headrequired, and specific speed are plotted vs. flow rate, as shown in FIG.9. The current pump operating performance curve is plotted vs. theoriginal or previous (at last maintenance/commissioning) pumpperformance curve and is adjusted for operating fluid properties.

In particular, the method of the invention for diagnosing rotatingequipment includes forming a hypothesis of component failure from the apump operating condition. Referring now to FIG. 10, to generate ahypothesis, diagnostic apparatus 24 first stores original data,represented by box 1010. Original data may further include geometricparameters of a pump system and the components of a pump system, a newor original condition pump performance curve, a previously measured pumpperformance curve, fluid properties data, maintenance record data andoutput display drivers. Original data may be used to construct anoriginal performance curve for rotating equipment or pump 14, as shownin FIG. 6, and represented in box 1012 of FIG. 10. The original datapossesses a recommended operating design regime 166, referred to as BestEfficiency Point (BEP) 164 when referring to a pump as shown in FIG. 6a.Recognized recommended operating design regime 166 is shown in FIG. 6aon an example pump curve. The acquisition of process variables fromprocess sensors that gather process data from pump or rotating equipment14 is represented by box 1014.

The method of the invention includes inputting process variables fromprocess sensors into computing device 38 (FIG. 1), as represented by box1016. A process data point is then obtained from the process variables,as represented by box 1018, which represents an operating condition ofrotating equipment or pump 14. Computing device 38 then compares theprocess data point with the original data, as represented in box 1020,to determine whether the operating performance is outside of recognizedrecommended operating design regime 166 (FIG. 6a). If the data point isdetermined to be inside the recommended operating design regime 166, thepump is operating efficiently. If the data point is determined to beoutside the recommended operating design regime 166, the pump isoperating inefficiently, as represented by boxes 1022 and 1024, in FIG.10.

In a preferred embodiment, computing device 38 also determines from acomparison of process data with original data whether the process datapoint, referred to in box 1018, is below the recommended operatingdesign regime 166, as shown in FIG. 6a, wherein the process data pointis designated 168. Operating a pump below the recommended operatingdesign regime 166 will cause a pump to experience possiblerecirculation. Therefore, diagnostic apparatus 24 (FIG. 2) will thenform a hypothesis that the pump is operating in an area of possiblerecirculation. Additionally, diagnostic apparatus 24 performs ananalysis to determine whether the process data point is operating abovethe operating design regime 166. If a pump is operating above therecommended operating design regime 166, as represented by data point170 in FIG. 6a, the pump will experience possible cavitation. Thus,diagnostic apparatus 24 will hypothesize that the pump may be operatingin an area of cavitation. This process is set forth in FIG. 11.

Referring now to FIG. 11, initially, original data having a recommendedoperating design regime 166 must be stored as represented in box 1110. Ahead vs. flow curve is then constructed from original data, as isrepresented in box 1112. Process variables are then acquired fromprocess sensors, as represented by box 1114, and the process variablesare input into computing device 38, as represented by box 1116. Anoperating performance data point is generated from the process variablesas represented by box 1117. Diagnostic apparatus 24 then determineswhether the pump is operating outside the recommended design regime 166,as represented by boxes 1118, 1120 and 1122.

If it is determined in box 1118 that the pump is operating outside ofdesign regime 166, as indicated in box 1122, then computing device 38determines whether a current operating performance data point indicatesa higher head pressure than the recommended design regime 166, asrepresented in box 1124. If so, a diagnosis of possible pumprecirculation is made by diagnostic apparatus 24, as represented in box1126. Additionally, diagnostic apparatus 24 determines whether theoperating performance data point indicates a lower head pressure thanthe recommended design regime 166, as indicated in box 1128. If thecurrent operating performance data point is lower than the recommendeddesign regime 166, then a diagnosis of possible pump cavitation is madeby diagnostic apparatus 24, as indicated in box 1130.

A similar analysis will be conducted regardless of whether the rotatingequipment is a pump or other type of rotating equipment. However, if therotating equipment is not a pump, but is a gas rotating machine such asa compressor, fan, turbine or blower, then the diagnosis in the case ofa current operating performance data point operating at a higher headpressure than the recommended design regime 166 will be surge as isshown in FIG. 5e for a compressor. An operating performance data pointindicating a lower head pressure than the recommended design regime 166will result in a diagnosis of stall as shown in FIG. 5e.

After a hypothesis has been formulated by diagnostic apparatus 24, inthe preferred embodiment diagnostic apparatus 24 performs a step ofverifying whether the process data point is outside the design regime166, shown in FIG. 6a, and determines the cause of degraded performance.The step of verifying the hypothesis may be performed by analyzingequipment monitoring variables generated by machine sensors. When pump14 is operating outside recommended operating design regime 166, oroutside BEP 164, pump component failure can be hypothesized and verifiedthrough the use of a second tier of condition monitoring variables andcurves.

Four secondary curves which permit confirmation of expected degradedpump components are included in this diagnosis method. The foursecondary curves (condition signatures) include: 1) dynamic pressuresensor spectra 172 shown in FIG. 7a; 2) velocity 173 and accelerationvibration spectra 174 obtained from an FFT analysis of accelerometersensor data shown in FIG. 7b; 3) bearing forces 180 vs. pump flow ratecurve, shown in FIG. 9; and 4) a break horse power 182 vs. pump flowrate curve, shown in FIG. 9.

The vibration spectra for both velocity and acceleration provide a basisfor diagnosing radial and trust bearings, damage to the pump impellerfrom recirculation or cavitation causing impeller imbalance, pump shaftimbalance wear of pump seals and wear plates and degradation ofancillary pump system components.

Dynamic pressure spectra 172 provides for a means of measuring pumppressure noise which will indicate insufficient net positive suctionhead leading to flashing or cavitation and for evidence ofrecirculation. Dynamic pressure pulsations are also known to increasedramatically whenever the NPSH available drops below the NPSH requiredas shown in FIG. 7c. The NPSH required is computed from themanufacturer's recommended levels adjusted for fluid vapor pressure andoperating temperature.

Examples of machine sensors, shown in FIG. 2, used to monitor pump andmotor system 10 include rotating machine vibration sensor 80, dynamicpressure sensor 82, motor vibration sensor 86, gearbox vibration sensor88, motor supply sensor 90, which may be a motor current or motorvoltage sensor, alignment sensor 92, seal leak detector or sensor 94,oil contamination sensor 96, viscosity degradation sensor 98, torquesensor 100, angular velocity sensor 102, corrosion sensor 104,ultrasonic thickness sensor 106, accelerometer 108, bearing temperaturesensor 110, bearing vibration sensor 112, displacement sensor 113, andan motor insulation resistance sensor 90 or other sensors to monitorequipment conditions.

Referring now to FIG. 12, it can be seen that in the preferredembodiment of the method, original data is stored as represented by box1210. Original data is used to construct an original performance curve,as designated by box 1212. An example of an original performance curveis shown in FIG. 6. Process variables are acquired from process sensors,as represented by box 1214. Condition monitoring variables are acquiredfrom machine sensors, as indicated by box 1216. A hypothesis is formedby diagnostic apparatus 24 regarding whether rotating machine and motorsystem 10 is operating outside of recommended operating design regime166, shown in FIG. 6a, as represented by box 1218, as shown in FIG. 10.If diagnostic apparatus 24 determines that rotating equipment 12 isoperating within recommended operating design regime 166, as indicatedin box 1220, or if diagnostic apparatus 24 determines that rotatingequipment 12 is operating outside recommended operating design regime166, as represented by box 1222, diagnostic apparatus 24 then performs averification step, as indicated by box 1224.

The general method described herein is applicable to pumps as well asother types of rotating equipment.

Referring now to FIG. 13, a method for verifying that a pump iscavitating includes constructing an original performance curve fromoriginal data, constructing a measured performance curve from processvariables, and then comparing the measured performance curve with theoriginal pump performance curve for determining if the pump iscavitating. By performing the comparison of the performance curves, itcan be determined whether a “droop” condition exists. An example of a“droop” condition is shown in FIG. 7d. If diagnostic apparatus 24determines that there is an observable droop, as indicated in box 1310,then a diagnosis can be made that cavitation exists, as indicated in box1312. This determination can be made because a droop condition indicatesthat insufficient net positive suction head is available, which resultsin pump cavitation.

Referring now to FIG. 14, an additional verification step that can beundertaken that includes acquiring a measured flow rate from processsensors, such as flowmeter 28. Diagnostic apparatus 24 may determine ifthe measured flow rate is less than the original flow rate, as indicatedin box 1410. If measured flow rate is less than the original flow rate,then a diagnosis of possible seal leakage is made, as represented by box1412. [45] Apparatus 24 then gathers and examines leak sensor data fromoptional seal leak detector 94, as represented by box 1418. Diagnosticapparatus 24 then makes a diagnosis of verification as represented bybox 1416.

The step of verifying a hypothesis and diagnosing specific problem areasby diagnostic apparatus 24 may be accomplished in a variety of ways andby examining a variety of machine sensors. The various machine sensorseach gives diagnostic apparatus 24 information about differentcomponents for verifying or disproving a hypothesis and providinginformation on various aspects of pump and motor system 10. Eachverification step is valuable for its information regarding a particularcomponent and for its ability to verify or disprove a hypothesisgenerated by diagnostic apparatus 24 and provides a root cause analysisfor the failure. Hereinbelow is a description of various verificationmethods that deal with different components of diagnostic apparatus 24.

Referring now to FIG. 15, a verification step includes acquiringoriginal condition dynamic pressure spectra having amplitude, frequencyand phase components as well as acquiring equipment condition monitoringvariables comprised of measured dynamic pressure sensor spectra havingamplitude, frequency and phase components. FIG. 7a shows an example ofdynamic pressure spectra wherein an increase in amplitude in frequencyregion 176 indicates a condition of recirculation and an increase shownin the amplitude of higher frequency region 178 indicates cavitation.

Diagnostic apparatus 24 makes a determination whether amplitude andfrequency components of measured dynamic pressure sensor spectra 172 isgreater than original condition amplitude and frequency components, asrepresented by box 1510. Diagnostic apparatus 24 then makes a diagnosisof possible pump cavitation, as represented by box 1512, or a diagnosisof possible pump recirculation, as represented by box 1514.

Referring to FIG. 16 and to pump cross sectional drawing FIG. 1b, anadditional verification step may be conducted wherein original conditionbearing velocity vibration spectra 174 and original conditionacceleration vibration spectra are acquired, as well as measuredvelocity vibration spectra and measured acceleration vibration spectra.Each of the measured and original condition acceleration and vibrationspectra has components of amplitude, frequency and phase. Diagnosticapparatus 24 compares at least one of these components selected from thegroup of amplitude, frequency and phase, as indicated in box 1610, todetermine whether possible impeller degradation exists, as indicated inbox 1612. It is noted that a continuous high level of vibration atimpeller resonant frequency indicates impeller 316 degradation.Increased impeller vibration occurs prior to impeller degradation.Therefore, impeller degradation is preventable. If, during a comparisonof the measured velocity vibration spectra, as represented in box 1610,it is determined that the measured vibration velocity spectra is higherthan original condition velocity spectra, then it is possible thatimpeller degradation exists. If a diagnosis of possible impellerdegradation is made by diagnostic apparatus 24, as represented by box1612; then in one embodiment of the method, a measured pump performancecurve is constructed as represented by box 1614.

A determination is then made whether a phase shift has occurred, asrepresented by box 1616, and if so, a diagnosis of possible fouling orcoating of an impeller in the rotating equipment is made, as representedby box 1618.

Referring now to FIG. 17, an additional verification step may beconducted wherein original data is comprised of original conditionvelocity vibration spectra 174 from rotating machine vibration sensor 80and original condition acceleration vibration spectra from accelerometer108, (FIG. 1) wherein the original and measured velocity andacceleration spectra have amplitude, frequency and phase components. Acomparison is made of at least one of the components selected from thegroup of amplitude, frequency and phase of the original conditionvelocity vibration spectra with at least one of the components of themeasured velocity vibration spectra, as well a comparison between one ofthe components of the original condition acceleration vibration spectrawith at least one of the components of the measured accelerationvibration spectra, as represented in box 1712. A determination is thenmade whether radial bearing 310 degradation exists, as represented inbox 1714.

Bearing frequency, resonant frequency and harmonics are distinct fromimpeller vibration, frequency and harmonics. Therefore, if the measuredvibration velocity amplitude is higher and the impeller frequency thanoriginal condition velocity vibration amplitude 173, then possibleimpeller degradation exists.

Referring now to FIG. 18, another verification step includes gatheringequipment monitoring variables, including pump input torque data fromtorque sensor 100 and pump shaft angular velocity data from angularvelocity sensor 102. With this condition monitoring data, a frictionaltorque is calculated for the rotating equipment, as indicated in box1810. A comparison of the measured condition frictional torque with theoriginal condition frictional torque is made, as represented by box1812, to determine whether bearings 310, 312 and seal 314 or wear platewear 320 is occurring. Diagnostic apparatus 24 will diagnose possibleseal 314, degradation if measured frictional torque is less than theoriginal condition frictional torque, as represented by box 1814.Alternatively, diagnostic apparatus 24 may diagnose bearings 310, 312seal wear 314 or wear plate 320 wear if the measured frictional torqueis greater than original condition frictional torque, as indicated bybox 1816. Frictional torque may be calculated from the equation below:${{{{Tp} = {\sum T}}’}s} = {{I \times \frac{N}{t}} = {{Tf1} + {Tb} + {Ts}}}$

where Tp=Torque to pump

I=Moment of Inertia of pump shaft/impeller assembly

N=Pump Speed, rpm

Tf=Fluid Torque

Tb=Frictional Torque of bearings

Ts=Frictional Torque of Seal/packing

The measured torque delivered by the motor can be compared to the motormanufacturer's recommended “torque to failure” to provide an earlywarning alert of imminent motor failure if the pump is not repaired andthe high torque condition is not corrected.

In an additional verification step, original data is comprised oforiginal vibration, acceleration and velocity spectra from rotatingmachine vibration sensor 80 or bearing vibration sensor 112, andmeasured velocity spectra from accelerometer 108, wherein both spectrahave amplitude, frequency and phase components. After a diagnosis ofpossible bearing degradation is made, as indicated in box 1816, acomparison is made of at least one of the components selected from thegroup of amplitude, frequency and phase of the original vibrationvelocity or acceleration at the radial bearing resonant frequency orharmonics or acceleration spectra, with at least one of the componentsof measured vibration velocity spectra 174 to determine whether themeasured vibration amplitude is greater than the original vibrationamplitude, as indicated in box 1818. If so, a diagnosis of radialbearing 310, FIG. 1b, failure is made, as indicated in box 1820.

Referring now to FIG. 19, measured radial vibration velocity spectra andmeasured radial bearing acceleration spectra are obtained from bearingvibration sensor 112. Each of the original and measured radial bearingand acceleration spectra possesses components of amplitude, frequencyand phase. A determination is made by comparing at least one of thecomponents selected from the group of amplitude, frequency and phase ofthe original radial bearing vibration velocity spectra with a componentof the measured radial vibration spectra as well as a comparison of theoriginal radial bearing acceleration spectra with at least one componentof the measured radial bearing acceleration spectra, as indicated in box1910. If at least one component of the measured vibration velocity andacceleration spectra is greater than the original component, then adetermination is made by diagnostic apparatus 24 of possible bearingdegradation, as indicated in box 1912.

Referring to FIG. 20, a further verification step requires a comparisonof original radial bearing 310 operating temperature with measuredradial bearing operating temperature as indicated in box 2010. Theoriginal radial bearing operating temperature is obtained from originaldata and the measured radial bearing operating temperature is obtainedfrom temperature sensor 118. If the measured radial bearing operatingtemperature is determined by diagnostic apparatus 24 to be greater thanoriginal radial bearing temperature, then a diagnosis of possible radialbearing degradation is made, as represented by box 2012.

Referring to FIG. 21, a further verification step is that of comparingat least one of the components of amplitude, frequency and phase oforiginal thrust bearing vibration velocity spectra with at least one ofthe components of measured velocity vibration spectra obtained frombearing vibration sensor 112. Additionally, a comparison is made betweenat least one of the components of original thrust bearing accelerationspectra with at least one of the components of measured accelerationspectra obtained from accelerometer 108, as represented by box 2110. Ifit is determined that at least one of the components of the measuredvibration velocity and acceleration spectra is greater than an originalcomponent of vibration velocity spectra, then a diagnosis of possiblethrust bearing 312 degradation is made by diagnostic apparatus 24, asrepresented by box 2112.

Referring now to FIG. 22, a further verification step may be conductedby comparing original thrust bearing 312 operating temperature obtainedfrom original data, and measured thrust bearing operating temperatureobtained from bearing temperature sensor 110 to determine whether thrustbearing degradation exists. If measured thrust bearing operatingtemperature is greater than original thrust bearing operatingtemperature, as indicated by box 2210, then a diagnosis of possiblethrust bearing degradation is made by diagnostic apparatus 24, asrepresented by box 2212. Original thrust bearing operating temperatureis obtained from original data.

Referring to FIG. 23, an additional verification step is conducted todetermine if sufficient measured available net positive suction headexists to operate pump 14 without cavitation. Measured available netpositive suction head is calculated by using a well known equation fromdata obtained from inlet pressure sensor 32 (FIG. 1). This determinationis made by determining if the measured net positive suction head isgreater than the net positive suction head required, as represented bybox 2310. If so, a diagnosis of possible cavitation is made bydiagnostic apparatus 24, as indicated in box 2312.

Referring now to FIG. 24, an additional verification step is made todetermine if sufficient measured net positive suction head availableexists to operate without cavitation. However, in the preferred method,the additional step of correcting the measured net positive suction headfor the measured operating temperature and fluid vapor pressure is made,as represented by box 2410. A determination is then made whether thecorrected measured net positive suction head available is greater thanthe required net positive suction head as represented by box 2412. Ifnot, then diagnostic apparatus 24 makes a diagnosis of possiblecavitation, as indicated in box 2414. The original required net positivesuction head and the fluid vapor pressure, both of which are availablefrom original data, are compared with the measured net positive suctionhead and the measured net positive suction head and calculated utilizingthe measured operating temperature of the process fluid is obtained bytemperature sensing device 30 (FIG. 1).

Referring to FIG. 25, a further verification step is conducted todetermine if thrust bearing degradation exists. Original axial thrustbearing displacement data is obtained from original data and measuredaxial thrust bearing displacement data is obtained from displacementsensor 113. A comparison of the original axial thrust bearingdisplacement data with measured axial thrust bearing displacement datais conducted to determine whether measured axial displacement data isgreater than original axial displacement data, as represented by box2510. If diagnostic apparatus 24 determines that measured axialdisplacement data is greater than original, and the bearing clearance isin excess of the manufacturer's recommended clearance, then a diagnosisof possible thrust bearing 312 degradation is made, as represented bybox 2512. It is noted that axial displacement sensor 113 measures thedistance from thrust bearing 312 to a reference housing 322. Typically,bearing 312 will move due to backpressure from rotating equipment 14which forces thrust bearing 312 into its race, thereby compressingbearing 312. A measurement may be made by an electronic proximity sensorsuch as those provided by Bently Nevada. Original axial thrust bearingdisplacement data is obtained from a manufacturer to provide anacceptable clearance specification for the thrust bearing. Displacementsensors may also be used to measure radial bearing clearance.

Referring now to FIG. 26, an additional verification step may beconducted to determine whether radial bearing 310 degradation exists. Acomparison is made between original radial bearing displacement dataobtained from original data with measured radial bearing displacementdata obtained from proximity sensor 113. If measured radial bearingdisplacement data is determined to be greater than original radialbearing displacement data, as indicated in box 2610, then diagnosticapparatus 24 determines that radial bearing degradation exists, asrepresented in box 2612.

Referring to FIG. 27, an additional verification step may be conductedto determine whether impending motor failure exists. This diagnosis ismade by comparing the manufacturer's original motor breakdown torque,which is obtained from original data, with measured electric motoroutput torque 100. Diagnostic apparatus 24 determines whether measuredmotor torque exceeds the manufacturer's recommended torque, as indicatedby box 2710. If so, a diagnosis of impending motor 12 failure is made,as presented by box 2712.

Referring now to FIG. 28, an additional verification step may be madewherein a display is generated of the performance curve and secondarycurve for comparison. Examples of secondary curves in FIG. 9 includeNPSH v. H&Q, BHP v. H&Q, efficiency v. H&Q, specific speed v. H&Q,bearing force v. H&Q, and Dynamic Pressure v. H&Q. To perform thisverification step, a selected secondary curve is constructed fromequipment condition monitoring variables, as represented by box 2812. Anoriginal secondary curve is constructed, represented by box 2810, and adisplay of the original performance curve and the secondary curve ismade for comparison, as represented by box 2814.

An additional step may be conducted to generate alerts if rotatingequipment 14 is operating outside of its recommended design regime 166or BEP regime 164 (FIG. 6a). One method of acquiring data sufficient togenerate an alert includes constructing an original performance curvefrom original data, as represented by box 2910, and then constructing ameasured performance curve from equipment condition monitoringvariables, as represented by box 2912. Optionally, diagnostic apparatus24 time-stamps the measured performance curve, as represented by box2914. Diagnostic apparatus 24 then compares the original performancecurve and the measured performance curve to determine the change in thepump performance variables, as represented in box 2916. If the changeexceeds the manufacturer's recommended range, then diagnostic apparatus24 generates an alert, as represented by box 2918, so that action may betaken to prevent operation of rotating equipment 14 outside of itsrecommended design regime 166 (FIG. 6a).

Additionally, diagnostic apparatus 24 may alert a controller to correctpump operating conditions to within the operating design regime 166, asindicated by box 2920.

Additionally, a similar procedure may be undertaken, except that insteadof constructing original performance curves and measured performancecurves, a process data point may be plotted from process variables and asecondary data point may be plotted from equipment condition monitoringvariables to determine if rotating equipment 14 is operating outside ofits recommended design regime 166 (FIG. 6a).

Referring to FIG. 30, the verification step may also include alerting acontroller to correct pump operating conditions to within a designcondition. The steps of alert and correction are accomplished byconstructing an original performance curve from original data, asrepresented by box 3210, constructing an original secondary curve fromoriginal data, as represented by box 3212, constructing a measuredsecondary curve from condition monitoring variables as represented bybox 3214, constructing a measured secondary curve from equipmentmonitoring variables, as represented by box 3216, and then comparing theoriginal performance curve with the measured performance curve todetermine the change in the pump performance variables, as representedin box 3218. If the change exceeds the manufacturer's recommended range,an alert is generated, as represented by box 3220. From the comparisons,diagnostic apparatus 24 may alert a controller to correct pump operatingconditions to within an operating design regime 166 (FIG. 6a), asindicated by box 3222.

Referring now to FIG. 31, an additional verification step includesdetermining whether valve cavitation exists. This determination is madeby comparing at least one of the components of amplitude, frequency andphase of measured dynamic pressure sensor spectra obtained from dynamicpressure sensor 82 (FIG. 1) with at least one component of originalcondition dynamic pressure sensor spectra obtained from original data,as represented by box 3310. If at least one component of measureddynamic pressure sensor spectra is greater than a component of originalcondition pressure spectra, as indicated by box 3310, then diagnosticapparatus 24 hypothesis possible valve cavitation, as indicated by box3312.

An additional verification step may be made by determining if sufficientcorrected measured net positive suction head available exists, such thatthe pump is not cavitating. This verification involves the step ofcorrecting the original net positive suction head required for operatingfluid temperature 30 (FIG. 1) and fluid vapor pressure, as indicated inbox 3314. Diagnostic apparatus 24 then makes a determination of whethermeasured net positive suction head available is greater than netpositive suction head required, as indicated in box 3316. If so,diagnostic apparatus 24 makes a determination that the diagnosis ofvalve cavitation is verified, as represented in box 3318. That is, ifNPSH_(R)>NPSH_(A), it is likely that the pump is cavitating. However, ifcavitation is detected and pump NPSH_(A)>NPSH_(R), then the source ofcavitation is a valve and not the pump 14.

An additional verification step includes determining whether measuredvibration spectra has increased in an expected pump cavitation frequencyrange. This determination is made by comparing at least one of thecomponents of amplitude, frequency and phase of measured vibrationspectra with at least one of the components of original conditionvibration spectra to determine whether at least one component ofmeasured vibration spectra is greater than a component of originalcondition vibration spectra, as represented by box 3320. If so, then themeasured vibration spectra has increased in the expected pump cavitationfrequency range, as indicted by box 3322, which verifies thedetermination of cavitation made above in box 3312.

Referring to FIG. 32, a further verification step may be made to verifypump cavitation. This diagnosis is made by comparing at least one of thecomponents of amplitude, frequency and phase of measured vibrationspectra with at least one of the components of original conditionvibration spectra to determine whether at least one of the components ofmeasured dynamic pressure spectra is greater than at least one of thecomponents of original condition pressure spectra, as represented by box3610. It is noted, however, that the comparison must be made in theappropriate frequency range. If it is determined that at least onecomponent of the measured dynamic pressure sensor spectra is greaterthan a component of the original condition pressure spectra, thendiagnostic apparatus 24 diagnoses valve cavitation, as represented inbox 3612.

Referring now to FIG. 33, an additional step of diagnosing a pumpdeadhead condition and sending a signal to shut down rotating equipment(FIG. 1) 14 or open valve 22 is made by acquiring control valve shaftposition data from control valve position sensor 34. From control valveshaft position data, a determination is made whether valve 22 is closed,as represented in box 3710. A determination is then made by comparingmeasured head with original condition head to determine whether head isat a maximum, as represented by box 3712. If so, a diagnosis of pumpdeadhead condition is made, as represented in box 3714, and diagnosticapparatus 24 sends a signal to the controller to shut down rotatingequipment 14 or open valve 22 to alleviate pump deadhead condition, asrepresented by box 3716.

Referring to FIG. 34, additional steps may be undertaken to determinewhether valve packing leakage or valve seal leakage is occurring. Thisdetermination is made by obtaining control valve flow data from originaldata and obtaining the control valve position from valve position sensor34 (FIG. 1). Diagnostic apparatus 24 then calculates valve flow from thevalve data at the control valve position, as represented by box 3810. Acomparison is then made between measured pump output flow withcalculated valve flow to determine if measured pump output flow isgreater than calculated valve flow, as represented by box 3812. If so,diagnostic apparatus 24 makes a diagnosis of valve packing leakage orvalve seat leakage as represented by box 3814. The equation used tocalculate valve flow is as follows:

Qv=Cv*A*(ΔP/SG)**0.5

where: Qv=Valve Volumetric Flow

Cv=Valve Flow Coefficient at position, y (valve data)

ΔP=Pressure Drop Across the Valve

SG=Liquid Specific Gravity

A=Flow Area of the Valve

Referring now to FIG. 35, additional steps may be undertaken to diagnosea plugged output pipe of rotating equipment 14. The diagnosis requiresthat original head and original outlet pump flow be obtained fromoriginal data and that measured outlet pipe flow be obtained fromflowmeter 28 (FIG. 1) and measured pump head be calculated from processvariables as described above. The method further includes operating thepump at a measured head equal to the original head, as indicated in box3910. Diagnostic apparatus 24 then makes a determination whether themeasured pump outlet pipe flow is less than the original outlet pipeflow at the identical head, as represented by box 3912. If the measuredflow is less than the original flow, then diagnostic apparatus 24 makesa determination of a plugged outlet pipe 20, as represented by box 3914.This method of comparison is based on the presentation of data as shownin FIG. 6b, where the original flow at original head is represented by apoint designated 180 and new measured flow point is designated 182.

Referring now to FIG. 36, additional steps may be taken to diagnose aplugged suction line by determining if original net positive suctionhead available is greater than measured net positive suction headavailable. In order to make this determination, the original flow rateand original net positive suction head available may be obtained fromoriginal data. Measured net positive suction head may be calculated fromthe inlet pressure. A comparison is then made between the original netpositive suction head available with the measured net positive suctionhead available. If the original net positive suction head available isgreater than the measured net positive suction head available, asindicated in box 4110, then a diagnosis of a plugged suction line 18 ismade by diagnostic apparatus 24, as indicated in box 4112.

Original data for the pump performance curve, FIG. 6, is typicallyprovided at a design speed determined by the manufacturer. However, if apump or rotating equipment is operated at a different speed than thedesign speed, then data must be corrected utilizing pump affinityequations. To calculate a speed change (N), the following affinity lawrelationships for flow (Q), head (H) and break horsepower (BHP) areutilized.

Q1/Q2=N1/N2 and H1/H2=(N1/N2)^(0.5) and BHP1/BHP2=(N1/N2)³${{Specific}\quad {Speed}\quad {Ns}} = \frac{N \times Q^{0.5}}{H^{0.75}}$

where: Ns is the specific Speed

N is the operating speed, rpm

H is the pump head, ft

Q is the flow rate, gpm.

Referring now to FIG. 37, original data is gathered, as represented bybox 4210, and an original performance curve is constructed, asrepresented by box 4212. Process variables are acquired, as representedby box 4214. The process variables are input into computing device 38(FIG. 1), as represented in box 4216. A comparison is then made betweenthe original performance curve and the measured operating point todetermine if rotating equipment 14 is operating outside of design regime166, as represented in box 4218. If rotating equipment 14 is operatingwithin design regime 166, then diagnostic apparatus 24 so indicates, asrepresented in box 4220. If the operating performance is outside ofdesign regime 166, diagnostic apparatus 24 so indicates, as representedby box 4222. If it is determined that rotating equipment 14 is operatingoutside of design regime 166, as represented by box 4222 (FIG. 6a), thena diagnosis of high bearing stress is made by diagnostic apparatus 24,as represented by box 4224. It is noted that impending bearing failurewill occur if a process operating point is either above or below a BEPregime 164 (FIG. 6a) on an original performance curve. If operation isoutside of a design regime 166, then bearing stress will be increasinglyhigher the further away from of design regime 166 that the process datapoint occurs. This is equally true for a high head-recirculation case ora high flow-cavitation case. This concept is illustrated graphically inFIG. 9a, where it can be seen that bearing forces are lowest at point184, which corresponds to BEP point 186.

If a diagnosis is made that rotating equipment 14 is operating outsideof recommended operating design regime 166, as represented by box 4222,an additional determination of whether a measured performance curve hasshifted downward as compared with the original performance curve is madeby diagnostic apparatus 24, as represented by box 4226. If so, adiagnosis of fouling or coating of an impeller 316 (FIG. 1b) is made, asrepresented in box 4228.

Referring to FIG. 38, in another embodiment of the invention, adetermination of whether pump 14 is operating in a recognizable,recommended operating design regime 166 (FIG. 6a) is made by comparing asystem head operating point with a measured performance curve. Thisdetermination is made by obtaining a calculated system demand curve at aspecific flow rate from original data, wherein the calculated systemdesign curve is determined by piping system geometry, fluid propertiesand pump operating conditions. Additionally, a calculated fluidfrictional head loss at a specific flow rate is determined from originaldata, wherein the calculated fluid frictional head loss is determined bypiping system geometry. Finally, a calculated velocity head at aspecific flow rate is gathered from original data wherein the calculatedvelocity head is determined by piping system geometry.

The method includes the steps of constructing a measured performancecurve from process variables as is known in the art, and which isrepresented by box 4410. Next, a system head operating point iscalculated from the calculated system demand curve at a flow rate, andthe calculated fluid frictional head loss and the calculated velocityhead, as represented in box 4412. Diagnostic apparatus 24 thendetermines if rotating equipment 14 is operating in the recommendedoperating design regime 166, shown in FIG. 6a, by comparing theintersection of system head operating point with the measuredperformance curve. If the operating point is outside the recommendedrange 166 then an alert can be generated. It is noted that pumps orrotating equipment produce flow and pressure, i.e., head, required by afluid system. The fluid flow system is constructed of pipe sections,pipe fittings (elbow, tees, etc.), valves, and vessels. Each of thesecomponents exhibit fluid friction, and as the fluid flow passes througheach element a pressure drop occurs due to friction with the element.The sum of the pressure drops throughout the system represents thesystem head and the pump provides exactly the required pressure head.

Some of the flow system components are variable frictional elements,such as a control valve. When a valve is closed, the pressure dropacross the valve increases and the pump must put out higher pressure tocorrespond to this reduction in flow.

When the pump pressure or head increases, the operating or measuredoperating point will move to the left on a head (H) v flow (Q) curve.This represents higher head (H) pressure and lower flow (Q). If thesystem head operating point moves too far to the left, indicatingincreasing head, the pump may be operating outside of its design regime166, shown in FIG. 6, and recirculation can occur. For the opposite caseof decreasing pressure and increasing flow, cavitation would be apossibility.

A pump, valve and piping system must be correctly engineered to providefor operation of a pump within a design regime 166, while delivering thepressure and flow required by the process.

Referring now to FIG. 39, a diagnosis of degraded rotating machineefficiency can be obtained by comparing measured rotating machineefficiency with original performance curves. This can be accomplished byacquiring rotating machine input torque data from torque sensor 100(FIG. 1), as represented by box 4510, and rotating machine shaft angularvelocity data from angular velocity sensor 102. The method calculatesthe measured rotating machine efficiency by calculating the input powerto the pump, as represented in box 4516, and by calculating the fluidoutlet power calculated from the flow sensor 28 and pump geometry,represented by box 4518. The rotating machine efficiency may then becalculated by the following equation:

Pump Efficiency, ηp=Pf/Pp

where η p is the pump efficiency

Pp is the power delivered to machine by the motor (also known as brakehorsepower)

Pf is the fluid power delivered by the machine.

Diagnostic apparatus 24 then determines whether measured pump efficiencyis less than original condition efficiency, as represented by box 4518.If so, then diagnostic apparatus 24 makes a determination that pumpefficiency is degrading, as represented by box 4520.

A further embodiment of the method of the invention is disclosed forconducting a field test to permit the actual measurement andconstruction of pump performance curves and secondary performance curvesthat can be compared with original performance data.

The method includes a mode for controlling the pump throughout itsoperating range consistent with the Hydraulics Institute test method,known in the art. This method provides for operating a pump through itsrange of operation by the driving of the valve I/P, 35 (FIG. 1), orvariable speed drive motor. This method can be used to construct pumpperformance curves in an automated fashion or for manually setting heador flow conditions to assist in the manual diagnosis of a rotatingmachine when a maintenance technician is looking to reproduce desiredoperating conditions.

The method operates the pump through its range of operation bycontrolling the rate of flow through the pump. The method is applicableto either a variable speed drive providing a full range of speedadjustment to the motor or via the control valve through a full range ofvalve flow control positions.

The method includes storing original data and adjusting a pump finalcontrol element to a desired setting, as presented in box 4610. The pumpfinal control element may be either a valve 22, FIG. 1, or a variablespeed drive connected to a motor 12. Process variables are acquired fromoperational rotating equipment 14 at the desired final control elementsetting, as represented in box 4612. The process variables are theninput into computing device 38. Diagnostic apparatus 24, FIG. 2,constructs measured performance curves from the process variables, asrepresented by box 4614, and repeats the steps of storing, acquiring,inputting and constructing a plurality of times wherein the pump finalcontrol element is adjusted to correspond to a defined set of testconditions for constructing the measured performance curves, asrepresented by box 4616. The measured performance points are stored, asrepresented in box 4618. An in situ performance curve and secondarycurve are finally constructed from process and condition monitoringvariables, as represented in box 4620.

In one embodiment of the field diagnostic test process, a means isprovided for manually establishing flow or head conditions, includingmanually adjusting the valve 22, manually adjusting the current or flowto motor 12, or other methods of manually adjusting the pump finalcontrol element to a desired condition.

An additional embodiment of a method for diagnosing rotating equipmentincludes storing original data having a recognized, recommendedoperating design regime 166 (FIG. 6a), as represented by box 5010 andacquiring a process variable from operating rotating equipment 14, FIG.1, wherein a process variable is selected from a group consisting offluid outlet pressure obtained from outlet pressure sensor 26, and fluidflow obtained from flowmeter 28, as represented by box 5012. The processvariable is then input into computing device 38, as represented in box5014, and a determination whether the process variable is within therecommended operating design regime 166 (FIG. 6a) is made, asrepresented by box 5016. If not, then diagnostic apparatus 24, FIG. 2,diagnoses that pump and motor system 10 is operating outside therecommended design regime 166, FIG. 6a, as represented by box 5018.

Whereas, the present invention has been described in relation to thedrawings attached hereto, it should be understood that other and furthermodifications, apart from those shown or suggested herein, may be madewithin the spirit and scope of this invention.

What is claimed is:
 1. An apparatus for diagnosing a power system whichincludes a rotating machine, the apparatus comprising: process sensorsfor generating process variables, said process sensors including: anoutlet pressure sensor positioned proximate an outlet of the rotatingmachine for determining rotating machine outlet pressure; and a flowmeter for determining a flow rate of product downstream of the rotatingmachine; said apparatus further including: an input/output device incommunication with said process sensors for receiving process variablesfrom said process sensors; and a computing device in communication withsaid input/output device, said computing device having a memory, saidmemory for storing data from said input/output device, said computingdevice for receiving original data including tables of machine geometry,machine installation parameters, original performance curves and fluidproperties of said pumped product, said computing device for comparingsaid process variables with said original data and for generating anoutput based upon said comparison.
 2. An apparatus according to claim 1,including machine sensors for generating condition monitoring variables,said machine sensors comprising: a rotating machine vibration sensormounted on the rotating equipment for determining vibration of therotating machine, said vibration sensor in communication with saidinput/output device for providing condition monitoring variablesthereto; and said computing device for comparing said conditionmonitoring variables with said original data for diagnosis of rotatingequipment degradation and for generating an output based upon saidcomparison.
 3. The apparatus according to claim 2, wherein said machinesensors further comprise: a gear box vibration sensor mounted on a gearbox for determining gear box vibration; and a motor supply sensormounted on electrical power supply service for determining electricalpower to a motor; an alignment sensor mounted on the motor fordetermining coupler alignment; wherein said motor vibration sensor, saidalignment sensor, said gear box sensor and said motor supply sensor arefor providing condition monitoring variables to said input/output devicefor providing said computing device with condition monitoring variablesto diagnose the rotating machine and alert an operator of impendingrotating machine maintenance.
 4. The apparatus according to claim 2,wherein said machine sensors further comprise a rotating machine sealleakage sensor mounted proximate a shaft seal on the rotating machinefor detecting seal leakage, said rotating machine seal leakage sensorfor providing condition monitoring variables to said input/output devicefor providing said computing device with condition monitoring variables.5. The apparatus according to claim 2, wherein said machine sensorsfurther comprise an oil contamination sensor mounted in a gearbox or onan oil sump for detecting oil contamination, said oil contaminationsensor for providing conditioning monitoring variables to saidinput/output device for providing said computing device with conditionmonitoring variables.
 6. The apparatus according to claim 2, whereinsaid machine sensors further comprise a viscosity degradation sensormounted proximate a gearbox for detecting oil viscosity degradation,said viscosity degradation sensor for providing condition monitoringvariables to said input/output device for providing said computingdevice with an oil condition monitoring variable.
 7. The apparatusaccording to claim 2, wherein said machine sensors further comprise adynamic sensor mounted on a pump casing for measuring pressure noise insaid pump casing for providing condition monitoring variables to saidinput/output device for providing said condition monitoring variables tosaid computing device for diagnosing pump recirculation and cavitation.8. The apparatus according to claim 2, further comprising a valveposition sensor mounted on said control valve and in communication withsaid input/output device, said valve position sensor for determining aposition of a shaft of said control valve.
 9. The apparatus according toclaim 2, wherein said machine sensors further comprise an corrosionsensor mounted on a rotating machine casing for measuring thedegradation of the rotating machine casing from corrosion, pumpcavitation or erosion, said corrosion sensor in communication with saidinput/output device for providing condition monitoring variablesthereto.
 10. The apparatus according to claim 2, wherein said machinesensors further comprise an ultrasonic thickness sensor mounted on arotating machine casing for measuring the degradation of the rotatingequipment casing from corrosion, pump cavitation or erosion, saidultrasonic thickness sensor in communication with said input/outputdevice for providing condition monitoring variables thereto.
 11. Theapparatus according to claim 2, wherein said machine sensors areintegrated with said input/output device and said computing device forcomparing measured performance signatures of the rotating machine at asecond time with an original condition signature at a first time, fordiagnosing degradation of the rotating machine.
 12. The apparatusaccording to claim 2, wherein said machine sensors further comprise: atorque sensor mounted on a shaft of said rotating machine, said torquesensor in communication with said input/output device for providing saidcomputing device with torque data; an angular velocity sensor mounted ona shaft of said rotating machine, said angular velocity sensor incommunication with said input/output device for providing said computingdevice with angular velocity data for computing input power to therotating machine, speed of the rotating machine, and rotating machineefficiency.
 13. The apparatus according to claim 2, wherein saidcomputing device serves as a host, said host in communication with acontroller proximate the rotating machine for controlling the rotatingmachine, said microcontroller having firmware for providing control setpoint to said rotating machine.
 14. The apparatus according to claim 2,wherein said computing device is positioned proximate a rotatingmachine, said computing device for providing a control set point forsaid rotating machine.
 15. The apparatus according to claim 2, furthercomprising a communication port for importing condition monitoringvariables from a portable handheld data logging device.
 16. Theapparatus according to claim 2, further comprising a process variabledigital bus in communication with networked intelligent devices.
 17. Theapparatus according to claim 2, further comprising a monitoring systemdigital bus in communication with intelligent network devices with acomputing device for collecting said condition monitoring variables. 18.The apparatus according to claim 2, further comprising conditionmonitoring subsystems for the rotating machine, said conditionmonitoring subsystems interfaced with the computing device via standardcommunication network interfaces for transmitting subsystem data over astandard communication network.
 19. Apparatus according to claim 18,further comprising an external processed data storage device for storingthe subsystem data wherein the apparatus is a network client having amemory database for storing data from a networked rotating machinesubsystem.
 20. The apparatus according to claim 2, further comprising aco-processor in communication with said computing device for providingspectral signal reduction of said condition monitoring variables fromsaid vibration sensor, said motor vibration sensor, said dynamicpressure sensor and said bearing vibration sensor.
 21. An apparatusaccording to claim 1, wherein said process sensors further comprise: aninlet pressure sensor positioned proximate an intake of the rotatingmachine for determining rotating machine inlet pressure; and atemperature sensor positioned upstream or downstream of the rotatingmachine for determining temperature of a process fluid.
 22. Theapparatus according to claim 1, further comprising an alert device forindicating when undesirable equipment conditions occur.
 23. Theapparatus according to claim 22, further comprising a contact closurefor shutting down the apparatus when said alert device indicates anundesirable equipment condition.
 24. An apparatus according to claim 1,further comprising a final control element, said final control elementresponsive to said output for adjusting the rotating machine and motorsystem for operating the rotating machine in a recognized recommendedoperating design regime.
 25. An apparatus according to claim 24 whereinsaid final control element is a control valve downstream of saidrotating machine for regulating back pressure.
 26. An apparatusaccording to claim 24, wherein said final control element is a variablespeed drive coupled to the motor, said variable speed drive foradjusting motor speed.
 27. The apparatus according to claim 1, furthercomprising a real time clock in communication with said computing devicefor time stamping process variables and said original data for timebased comparison.
 28. The apparatus according to claim 1, furthercomprising a display for representing a performance signature at a firsttime and a second time.
 29. The apparatus according to claim 1, furthercomprising a co-processor with a spectral analysis engine for processingsignals from frequency domain sensors.
 30. The apparatus according toclaim 1, further comprising a network communication port incommunication with said input/output device, said network communicationport for communicating said output to a network.
 31. An apparatusaccording to claim 1, further comprising a communication device forcommunicating data from said computing device to a networked host. 32.The apparatus according to claim 1, wherein said computing device ispowered by and communicates over two wires.
 33. The apparatus accordingto claim 1, wherein said computing device is powered by and communicateswith either 3-wire or 4-wire networks.
 34. The apparatus according toclaim 1 including multiplexer inputs in order to diagnose more than onesaid rotating machine.